Ottmaja conbabty



' May 26, 1931. o. CONRADTY INCANDESCENT LAMP Filed NOV. 5, 1927 JMMtW Ottm WNMII Patented May 26, 1931 PATENT; OFFICE mm CONRADTY OF NUREMBERG, GERMANY INCANDESGENT LAMP Application filed November 3, 1927, Serial 110. 230,758, and in Germany June 24, 1927.

My invention relates to improvements in incandescent lamps, and more particularly in the construction of the base carrying the bulb. The'object of the improvements is to provide an incandescent lampin which the base is not subject to corrosion by acid and other gases such as are produced in chemical laboratories, factories, and the like, and with this object in view my invention consists in constructing the base of materials which are not affected by acids and atmospheric influences. For example, the current conduct ing elements may be composed of a suitable non-corrosive metal such as stainless steel. or metal alloys capable of resisting acids and atmospheric influences, such as silicon steel. However, in man cases even such materials are not sufficient y resistant against corrosion and destruction by acids, and in such instances it may be necessary to provide elements composed of carbon or of coal or graphite.

For the-purpose of explaining the invention an example embodying the same has been illustrated in the accompanying drawing, the said drawing showing an incandescent lamp in sectional elevation.

As shown in the said drawing the base of the lamp comprises an outer substantially cylindrical current conducting member composed of a suitable non-corrosive metal or carbon material and formed with the usual screw threads 6 for fitting in a holder of normal construction, and an inner current conducting member in the form of a tapering elongated block likewise composed of a suitmembers a and I) while in plastic form and allowed to set into a hard body. The members a and b constitute the terminals of the lamp, and have the leading-in wires f and 9 connected thereto. To insure a reliable electrical connection with the said wires the terminals a and b may, when composed of carbonmaterial, be provided with a metal coating on a portion of their inner surfaces, and the leading-in wires soldered to such coating.

I have found that an incandescent lamp constructed as described herein is absolutely safe under most exacting conditions.

I claim:

1. An incandescent electric lamp comprising a bulb, and a base having an outer cylindrical current terminal composed of acid roof material and adapted to be inserted in a holder, an inner current terminal composed of acid proof material and mounted concentrically of said outer terminal and an insulating'body disposed between said terminals.

2. An incandescent electric lamp as set forth in claim 1 having outer and inner terminals composed of carbon.

OTTMAR CONRADTY.

able non-corrosive metal or carbon material and located with its inner portion concentrically within the member a. For simplicity 40 only representations of carbon current-conducting members are shown since the construction and arrangement of the members is substantially the same'whether they be composed of carbon or non-corrosive metal. Surrounding the member I) and separating it from the member a is arran ed asuitable insulating body d by means 0 which the membars a and bare mechanically connected and electrically separated from each other, the body (1 preferably being molded about the 

